Author Topic: Two Cylinder Engine  (Read 21455 times)

Offline Roger B

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Re: Two Cylinder Engine
« Reply #120 on: December 01, 2018, 02:47:08 PM »
The adjuster holes in the tappets were tapped M4 and the sharp edges were removed. Next I milled some reliefs in the bottom of the rocker support to clear the cylinder head fixings and then moved on the camshaft area. The tappets run in Oilite bushes that are turned down versions of the tophat bushes that the shaft runs in.
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #121 on: December 01, 2018, 02:52:34 PM »
The tappet bushes were pressed in in one operation as there is zero clearance between them.

I then needed to extend the base of my cam milling fixture to accept the longer camshaft. Finally I milled 2mm keyways in the crankshaft and camshaft. The single just uses grubscrews but I want to be more certain with this engine as there is also a water pump to drive and possibly fuel injection.
Best regards

Roger

Offline Art K

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Re: Two Cylinder Engine
« Reply #122 on: December 01, 2018, 05:42:53 PM »
Roger,
Looking good, moving right along.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Craig DeShong

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Re: Two Cylinder Engine
« Reply #123 on: December 06, 2018, 09:38:05 PM »
Great progress Roger.   :ThumbsUp:
Craig

Offline Roger B

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Re: Two Cylinder Engine
« Reply #124 on: December 19, 2018, 07:23:28 PM »
Thank you both  :)

A little bit more on this one. I broached the keyways in the crankshaft timing gear and the camshaft milling jig adaptor. Next step is the valves. These are turned from M4 x 40mm A2 Stainless Steel caphead screws as before. The first step was to true the heads to the shanks ending up at 6.6mm diameter. For the next step I went back to the Hobbymat spring collet system with a 1/4 collet to hold the heads for center drilling and turning the shanks down to 2.5mm (also using the DTI on the cross slide). The blanks were then radiused under the head with a 3mm form tool. As you can see There are 6 valves to allow for some mistakes  :toilet_claw:
Best regards

Roger

Online Ye-Ole Steam Dude

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Re: Two Cylinder Engine
« Reply #125 on: December 19, 2018, 08:27:11 PM »
Hello Roger,

That is some pretty work.

Have a great holiday,
Thomas

Offline Roger B

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Re: Two Cylinder Engine
« Reply #126 on: December 27, 2018, 12:50:58 PM »
Thank you Thomas  :ThumbsUp:

On with the valves. I cut of the remaining threads, cleaned up the end and then checked the fits with an offcut of brass drilled and reamed 2.5mm. The seats were then cut at 45░ and the heads were thinned.

The valve guides were made from Cu Sn8 bronze rather than RG7 as I could get smaller diameter rods and less wastage (the smallest RG7 is 13mm). They were drilled 2.3mm and reamed 2.5mm. The outside was turned to 8mm and the guide to 6.05mm as a press fit in the head. This bronze seemed less 'snatchy' than the RG7 and produced annoyingly long curly swarf.
Best regards

Roger

Offline steamer

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Re: Two Cylinder Engine
« Reply #127 on: December 27, 2018, 02:56:16 PM »
Coming along nicely!

Dave
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Damned ijjit!

Offline Roger B

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Re: Two Cylinder Engine
« Reply #128 on: December 27, 2018, 04:17:34 PM »
Than you Dave  :ThumbsUp:

The valve guides were held in the ER11 chuck to turn the spring seating to 4.75mm and were then pressed into the head one at a time with my bench vise.

I had been planning to use the seat cutter I had made for my vertical engine to cut the seats forgetting the ports and valves on this engine are slightly bigger otherwise I would have made the cutter at the same time as the valves. This time I tried to use the ER11 collet chuck to hold the head but even with the shorter collet it was not stable so I went back to the 1/4" spring collet.
Best regards

Roger

Offline Florian Eberhard

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Re: Two Cylinder Engine
« Reply #129 on: December 27, 2018, 05:48:09 PM »
Hey Roger

Well done, that is some nice work!
Just be careful with CuSn8. That is some nasty stuff to drills! It can (but doesn't have to) happen that the drill gets stuck pretty fast and then breaks immediately. A bit like stainless steel but with less signs what is going to happen.

Cheers Florian (just beginning to bring everything to my new shop :) )

Offline Roger B

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Re: Two Cylinder Engine
« Reply #130 on: December 27, 2018, 06:19:48 PM »
Thank you Florian  :ThumbsUp: With the drills I have (normal as far as I know) it seemed easier than the RG7. I did use a cutting lubricant for drilling and reaming.

How long before the new shop is up and running?
Best regards

Roger

Offline Florian Eberhard

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Re: Two Cylinder Engine
« Reply #131 on: December 27, 2018, 06:55:54 PM »
Hi Roger

Well you had good luck with the drills then  :D

My shop? Aehm a bit difficult to say, I hope to have moved everything until the end of next week.
But I am planning to make a few improvemens (felt wipers for the guideways on my lathe and renew the ones of my milling machine and a bunch of small things like repositioning some lubrication cups which are hard to reach, swarf guard for the column of my milling machine etc.)

So the answer is it depends on how you define "up and running" ;)

-> I'm off to my new shop, painting the workbench for the second time (final pass)
I'll put a picture in the shoutbox when I get back up  ;)

Florian

Offline Roger B

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Re: Two Cylinder Engine
« Reply #132 on: December 28, 2018, 06:00:13 PM »
I cut off the last of the thread and then cut the seat. There is no need to radius under the head of the seat cutter. The cutting edges were made with a half round swiss file and the seats were cut by hand using a T handle hex key.
Best regards

Roger

Offline Admiral_dk

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Re: Two Cylinder Engine
« Reply #133 on: December 28, 2018, 08:01:56 PM »
Hi Roger

I like your idea of using a Allan head bolt as the cutter - simple and clever  :ThumbsUp:

It looks like you got a nice result from cutting the first two - was it easy to control the cutter ?

Best wishes

Per

Offline Roger B

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Re: Two Cylinder Engine
« Reply #134 on: December 29, 2018, 08:59:29 AM »
Thank you Per  :ThumbsUp:

As there is no real clearance the cuts are very fine. The seats you can see probably had 10 turns of the cutter (20 half turns  ;) I don't have fully rotating wrists)
Best regards

Roger